In the treatment of gas streams, de-watering processes generate extracted water that may contain traces of contaminants originating from the principal stream. In the case of natural gas, these contaminants include hydrogen sulphide, sulphur dioxide and mercaptans. Disposal of water containing contaminants of this type can be subject to environmental restraints.
Where natural gas is being used to power consumer vehicles, it is desirable to provide a compact gas compressor that can operate at a consumer's residence to refuel a vehicle. It is necessary in many such situation to remove the residual moisture in the natural gas during the compression process. The extracted water thereby produced cannot be released locally into the environment because of the contaminants present therein. Apart from issues relating to hazards, even trace smells of organic or sulphurous components from a natural gas stream would suggest to a consumer that a leak existed in the compressor system.
If the contaminated extracted water were to simply be accumulated, then frequent service calls would be required to remove the accumulated liquid. This invention provides a means for extending the servicing intervals for such a system.
While described in respect of removing water from natural gas, the invention can be applied to any case where water is removed from a fluid and a disposal problem exists due to the presence of contaminants in the water so removed.
The technology for drying gas and liquid streams is well established. It includes absorption and condensation methods and the use of membrane separation systems. Examples of these technologies, used separately and in combination are U.S. Pat. Nos. 5,034,025; 5,071,451 and 5,240,472 as well as the prior art referred to therein.
Further examples of prior art in this field include the published application PCT/US84/01372 (WO85/01058) filed by Pall Corporation of Glen Cove, USA and U.S. Pat. No. 2,747,681 to Schuftan et al. In this Pall application water contained in purge gas is condensed-out leaving H.sub.2 S gas which is adsorbed in iron sponge beds with residual purge gas being reintroduced into the gas flow. No provision is made, however, to separate-out residual contaminants contained or mixed in with the water condensate, and then to release contaminant-free water into the environment.
In the case of Schuftan the desiccant bed is regenerated using gas from the main gas stream as a sweep gas. Water condensate is released from the system through a drain pipe without any provision for removing residual contaminants present in such water.
None of the known prior art references address the objective of treating extracted water to separate it into purified water and residual components in order to permit the removal of the contaminant-free water from the desiccation apparatus for disposal as such. No references address the issue of separating of contaminants from the extracted water and disposal of such contaminants separately from such water, with the purified water being released into the environment in a contaminant-free form. The invention herein address these concerns.
The invention in its general form will first be described, and then its implementation in terms of specific embodiments will be detailed with reference to the drawings following hereafter. These embodiments are intended to demonstrate the principle of the invention, and the manner of its implementation. The invention in its broadest and more specific forms will then be further described, and defined, in each of the individual claims which conclude this Specification.